In recent years, type A influenza (H1N1) called a new type of influenza has spread around the world, which has become a social problem. Therefore, to prevent infection with the new type of influenza virus from spreading is a very important issue. Early detection of people infected with the virus is necessary to prevent the infection from spreading, and it is most effective to isolate people with suspected influenza virus infection before symptoms appear if possible. To this end, to technically detect a possibility of having coming into close contact with an infected person is desired.
Furthermore, when an incident, an accident, or a traffic accident (referred to as “something like an incident” from here on) occurs, witness testimony is very important because it results in the quick solution of the something like an incident, though a problem is that it is difficult to search for witnesses.